Masking method used in surface treatment process

ABSTRACT

A masking method used in a surface treating process is disclosed. The masking method includes the following steps: preparing paint, coating the paint on inner surfaces of a hole in a workpiece, and curing the paint, thereby forming a protection coating layer on the inner surfaces of the hole to protect the inner surfaces of the hole during a surface treatment process. The paint is resistant to the surface treatment process, and includes resin and solvent. A surface tension of the paint is smaller than or equal to 22 mN/m.

BACKGROUND

1. Technical Field

The present disclosure relates to masking methods, and particularly to a masking method for masking inner surfaces of holes of a workpiece in a surface treatment process.

2. Description of the Related Art

During a surface treatment process, such as anodizing, of a workpiece, holes of the workpiece can be protected from the treatment process by a masking method. In a masking method, protective rubber plugs can be employed to block or plug the holes, such that the holes are protected from being treated. However, if the holes are irregular or have a complicated shape, the protective rubber plugs cannot tightly adhere to the inner surfaces of the holes so as to completely block the holes. If the holes are too small, insertion of the protection rubber plugs is difficult.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views.

FIG. 1 shows one embodiment of a protection coating layer protecting a plurality of holes in a workpiece.

FIG. 2 is a data table presenting the testing results obtained from testing of three test examples of the embodiment and a comparative example.

DETAILED DESCRIPTION

FIG. 1 shows a workpiece 10 having a plurality of holes 11. The workpiece 10 is treated by an anodizing method, and inner surfaces of the holes 11 are not treated. In one embodiment, the holes 11 are protected by a protection coating layer 30. The holes 11 can be in any shape. A depth of the holes 11 is in a range from about 0.1 millimeters (mm) to about 15 millimeters (mm), and a width of the holes 11 is in a range from about 0.9 mm to about 10 mm.

The protection coating layer 30 is formed on inner surfaces of the holes by coating a layer of paint on inner surfaces of the holes 11. The paint includes resin, solvent, and additive agents. A surface tension of the surface of the layer of paint is smaller than or equal to about 22 milliNewtons per meter (mN/m). A solid content of the paint is smaller than or equal to about 30%. The resin is resistant to acid and alkali corrosion, and is selected from one or more of the group consisting of fluororesin, silicon resin, silicon rubber, epoxy resin, acrylic resin, and polyurethane resin. The surface tension of the resin is reduced by adding one or more of the following functional groups attached to the resin: fluoro-functional groups, aliphatic hydrocarbons, and organosilicon functional groups. The solvent is an organic solvent selected from one or more from the group consisting of isoparaffin solvent, toluene, ethyl acetate, acetone, and butanone, as long as the resin can be dissolved in the solvent. The additive agents are selected from one or more of the group consisting of diluents, curing agents, initiators, sensitizers, adhesion promoters, dispersing agents, wetting agents, thickening agents, and antifoaming agents. In other embodiments, the additive agents can be omitted.

One embodiment of a masking method for protecting the holes 11 of the workpiece 10 is illustrated as follows. First, a paint having a surface tension smaller than or equal to about 22 mN/m is prepared. Next, a layer of the paint is uniformly coated on the inner surfaces of the holes 11. Finally, the layer of the paint is cured to form a protection coating layer 30 on the inner surfaces of the holes 11. A thermal curing method or a photocuring method can be employed to cure the layer of the paint, depending on the type of paint used. In the embodiment, a thickness of the protection coating layer 30 is in a range from about 0.1 micrometer (μm) to about 5.0 micrometer (μm), such as, for example, 1 μm, 2 μm, and 3 μm. The thickness of the protection coating layer 30 is adjusted by the percentage of solid content. FIG. 2 presents the testing results obtained from three test examples of the embodiment (serving as the experimental group) and alongside the testing results obtained from a comparative example (serving as the control group), to show or demonstrate that the protection coating layer 30 formed in and in accordance with the embodiment is better (in performance) than a protection coating formed by conventional methods. The paint can be coated or applied on by brush coating, spray coating, curtain coating, or the like.

The surface tension of the paint is smaller than or equal to 22 mN/m, such that a layer of the paint is easily coated on the inner surfaces of the holes 11, thereby forming a protection coating layer 30 completely adhered to the inner surfaces of the holes 11. Even though the holes 11 are irregularly-shaped or hard to access, the protection coating layer 30 cannot be easily broken. Even though the holes 11 are relatively small, the protection coating layer 30 cannot be detached from the inner surface of the holes 11. In addition, because the thickness of the protection coating layer 30 is small enough, after the surface treating process is performed, the protection coating layer 30 does not need to be removed. Thus, a production process is simplified, reducing a production cost by adopting the masking method for protecting the holes 11 of the workpiece 10 in accordance with the embodiment.

In other embodiments, when the workpiece 10 is treated by other surface treatments that are not acidic or alkaline, the resin is made to be resistant to the corresponding surface treatment. For example, if the workpieces 10 are to be treated by plating, then the resin is resistant to a plating solution.

Depending on the embodiment, some of the steps described above can be eliminated, while other additional steps can be added, and the sequence of steps can be changed. It is also to be understood that the description and the claims drawn to a method can include some indication in reference to certain steps. However, the indication used is only to be viewed for identification purposes and is not a suggestion as to an order for the steps.

It is to be understood, however, that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in the matters of shape, size, and arrangement of parts within the principles of the embodiments to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A masking method used in a surface treating process, comprising steps as follows: preparing a paint, the paint being resistant to the surface treating process, the paint comprising a resin and a solvent, and having a surface tension smaller than or equal to about 22 mN/m; coating a layer of the paint on an inner surface of a hole in a workpiece; and curing the paint, thereby forming a protection coating layer on the inner surface of the hole to protect the inner surface of the hole being treated in the surface treating process.
 2. The masking method used in the surface treating process of claim 1, wherein the surface treating process comprises an anodizing process, the resin is resistant to acid and alkali corrosion, the resin is selected from one or more from the group consisting of fluororesin, silicon resin, silicon rubber, epoxy resin, acrylic resin, and polyurethane resin.
 3. The masking method used in the surface treating process of claim 1, wherein a thickness of the protection coating layer is in a range from about 0.1 μm to about 5 μm.
 4. The masking method used in the surface treating process of claim 1, wherein the paint further comprises an additive agent, the additive agent is selected from one or more from the group consisting of diluents, curing agent, initiator, sensitizer, adhesion promoter, dispersing agent, wetting agent, thickening agent, and antifoaming agent.
 5. The masking method used in the surface treating process of claim 1, wherein the solvent is selected from one or more from the group consisting of isoparaffin, toluene, ethyl acetate, acetone, and butanone.
 6. The masking method used in the surface treating process of claim 1, wherein the resin is added by fluoro functional group, hydrocarbon aliphatic functional group, or organosilicon functional group.
 7. The masking method used in the surface treating process of claim 1, wherein a solid content of the paint is smaller than or equal to about 30%.
 8. The masking method used in the surface treating process of claim 1, wherein the paint is coated on the inner surface of the hole in the workpiece by a brush coating.
 9. The masking method used in the surface treating process of claim 1, wherein the paint is coated on the inner surface of the hole in the workpiece by a spray coating.
 10. The masking method used in the surface treating process of claim 1, wherein the paint is coated on the inner surface of the hole in the workpiece by a curtain coating. 